Controllable resistance device



Aug. 7, 1928. 1,680,189

' H. J. WIEGAND ET AL CONTROLLABLE RES I STANCE DEVICE iled Nov. 2, 1923 Patented Aug. 7, 1 928i UNITED STA cousin, A CORPORAION on WIsdonsm..

Application filet} Noveinber 2,1923;

conirnonnnnnn nnsrsflmon ADEVICE.

particularly to tro1 reiatively In a co-pending application of Wiegand, filed J u1y 652,462 is diclosed and and improvemcnt in devicesof such character and the present invention devices to provide and conhigh res1stance values.

Henry J. 18, 1923, [Seiia1 No. claimed an invention has among its objccts that of otherwiSe and further improving such devices Another object is troiiabie resistance characteristics may be thatoi pr0viding a condevice whose operatrve more readily and accurately predetermined and controlled.

Anotherj object is that of dev1ce wherein provision 1s made providing such a f0r- 1n creased facility of circuitconnection and physieai supportthereof. Other objects and advantages W111 boreinaiter appear.

In accordance with the teaching of said oo-pendingapplication,- an 1nSulat-ing disk or its equ1vaient having a perlpheral'conduct1ve coatmg of high res1stance 1s mounted for rotation -With reference to a relatively fixed bruSh of graphite or other suitable and -rclatively soft conductive material, said conductive coa.ting having its continuity intcrruptcd at a limited region and having, ad

acent such. regron,

an electrical connection with its mounting and operating shaft or with an ec1uivalent conductive element 1ocated substantially making contact with a orting2;- element or part provided with a suitable circuit terminal.

axiaily of the disk and This arrangement prov1des, durnig service, for some degree of accretion of mater1al of restoration and also the conductrve coating by means of material of the brush therethe brush or other cause.

possible loss of such result, of rubbing by Also sonne degree of roughening of the surface of the insulating disk is contemplated whereby the conductive coat1ng may be originaily applied, as

well as restored, by simple rotation of the disk with reference to In accordance with the brush. r

the present invention it is proposed to provide for more positiveIy,

accurateiy and unifo the ress'tivity of rmly predetermining the conductive coating 0f the in more fui1y other plurality o f grooves extending 1nd1rections havrng a c1r-f unit lengths of such path Serial No. 672,329.

service of the preselected value of such:iesistivity and aiso enabling and facilitating quantity production of devices ha ving similar operativecharacteristics; In the accompanyihg drawing wherein is illustrated an embodiment which the invention may assume in practice,

-'Figure 1 is a perspective vieW of such a device together wi-th an "associated instrumentality.,

Figs. 2 and 3 are detail views illustrat-i ing more fully certain elements of Fig. 1.

Fins. 4 and 5 are detail views illustrating features of Fig; 1 while, Figs. 6 and? are detail vieWs illfis'tratir1g a slight modification'of the element ShoWn in Figs. 4 and 5;

As iliust1ated, particularly in Figs. 4: to 7, inclusive, it is hereih proposed to spcialiy prepalre or treat the peripheral surface of insulating disk 10 in. ways adapting the same to receive and: permanentiy retain definite reduced quantities of conduotive n1aterial thror1gout unit lengths of the current path about said disln such-quantities of the conductive nnaterial to be maintained trona 1naterial ofthe brush 16 and to be- 01igihally T0 such end it is poposed to provide the circumferentizfl surface of s'aid. disk with a regular and relatively portance in prdvidirrg circiiin-feientiai' cohroov, and of the conductive nnt is desimble foi puposes of distribtirig Fr0in the foregdirig it rsults that, thrbugh otimferential and also an axial component. Such c1rcurnferiitrdl c'orhponent is of 1m tinuity of the material there n, Wheis the axia1 c0riipoand equalizing abrasion upon the coacting surface of thebiiish;

predermimtim and cr1troi of the r1mbe'r and size of the .c1rou1nferentialiy ,continuous grooves provided, the resistivity of the conductive path about the disk and aiso of may be very accu-' ateiy predetermined and controlled. Also,

production of devices having uniform corresponding ohmic and other characteristics is enabled and facilitated. in pra the afdredescribed expedients quantity ample as the continuons spiral illustrated at 10 and 10 in F igs. 4 and 6 or the cross hatehed form shown at 10' and 10 in Figs; 5 and 7 in which latter f0rms the current is tiansmitted through a multiplicity of zig za'g paths. Also the grooves may be applied to a disk having straight edges as in Figs. 6 and 7 or having curved edges as in Figs. 4 and 5. The af0redescribed disk may comprise hard rubber or other preferred insw lating material whereas in practice the same is preferab y rigidly secure-d upon a suitable operating shaft 11 Which is rotatably mounted within axially spaced supports comprising an insulating block or board 12 :and a Conductive strip 13 suitably secured thereto. Saidconductive strip is preferably provided With a suitable external terminal device and is utilized to provide for exteriial electrical connection of said operating shaft or a part in electrical connection therewith. A spring Washer 14 is preferably interposed between the disk and conductive supporting strip to provide for'firm and resilient engagement between the conductive supporting stiip13 and an enlarged head 15 of said operating shaft. r

' Brush 16is carried by a si1itable holder, Which may preferably comprise an elOngated metallic block 17 having a transverse bore Or passage to receive said brush and also having reduced and threaded opposed terminal portions adapted to receive 'suitable conductor clanxping nuts, as illus- :trated. One of the terminal portions of Said block is adapted to penetrate the insulating' board 12 for securement of the brush holder to the latter Whereas a spring clip 18 is carried by the other of said'terminal portions for forcing the brush into positive contact with the periphery of disk 10.

As a .convenient means for electrically connecting and physically supporting the device with reference to anassociated instrumentahty a stfif but flexible supporting jumper 19 may be provided. Said'jumper' is provided with a suitable eye for direct securement to a terminal of the associated device, and is further provided at its opposite-end with another eye for direct secure ment to the last mentionedterminal portion of block l7. Said eyes may be angularly displaced with reference to one another. Said jumper is further provided With an outpositioning of the dcvicc. 'scribed construction and arrangement, 1n-

' contacter t1vely soit struck lug portion 20 adapted to co-act with an edge portion of the insulating support 12 to assist in supporting and permanent The aforedecluding fiexibility of said jumper thus provide for permanent mounting of the device in practicallyany desired relation to the associated instrumentality.

In practice the operating shaft may be provided With an adjustable insulated extension as shoWn.

lVhat we'claim as new' and desire to secure by Letters Patent is:

1. In a variable resista1icedevice, the combination withrelatively movable resistor and contactor elcments each comprising relatively s'oft inaterial, of an insulating support for said resist0r to co-act with said'contactor, said support liaving continuons grooves, to contain material of said resistor, and intermediate ridges t0 efiect abrasion of said contacter. A

2. In a variable resistancedevice, the combination with relatively movable resistor and elements each comprising relamaterial, of an insulating support for said rcsistor t0 co-actwith said contactor, said support having v continuons grooves, to contain inaterial of said resistor, and intermediate ridges to eiect abrasion of said contacter, said grooves and ridges extending in directions having a component parallel" to the direction et relative movement of said re[sistor and contactor.

3. In a variable resistance device, the conr bination with relatively movable resistor and contacter elements each comprising relatively soft material, of' an insulating support :Eor said resistor t0 co-act with said contactor, said support having continuons grooves, to contain matcrial oi said resistor, and intermcdiate ridges to efiect abrasion of said contactor, said grooves and ridges extending in directions having a. component parallel to the direction et relative movcment of said resistor and contacter, and also having a component ahgularlyrelated to such direction.

In= witness whereot, We have hereunto subscribed our names.

. HENRY JQ IWIEGND.

HORACEN. PACKARD. 

